Effect of enzymatic hydrolysis on surface activity and surface rheology of type I collagen.

We describe the adsorption behaviour and rheological properties of a calf skin type I collagen, and of its hydrolysates obtained using a Clostridium histolyticum collagenase (CHC) under moderate conditions (pH 7, 37°C). The effect of CHC concentration (2×10(-9)-2×10(-6)M) and incubation time (35-85min) was studied and optimised to achieve the highest decrease of surface tension and the highest dilational surface viscoelasticity of the adsorbed layers. SDS-PAGE electrophoresis and reverse-phase high performance liquid chromatography (RP-HPLC) were used to characterise the hydrolysis products. The results show that even simple modifications (heat treatment, pH change, partial hydrolysis) of collagen enhances its surface properties, especially in terms of surface dilational elasticity modulus. The use of low enzyme concentration (CHC-to-collagen molar ratio of 4×10(-3)) and short incubation time (<45min) results in moderately hydrolysed products with the highest ability to lower surface tension (γ=53.9mNm(-1)) forming highly elastic adsorbed layers (surface dilational elasticity, E'=74.5mNm(-1)).